Primary care houses the hidden mental health network in the United States, providing over 50% of the treatment for mental health needs. Depression is the most common health problem treated and has considerable impact on health and function. As gatekeeper, the primary care physician is expect to recognize depression and treat or refer as appropriate. Failure to recognize depressive symptoms can lead to misdirecting resources. Although depressive symptoms are frequent in primary care, under-recognition of depression is a serious problem. Few data are available to explore the impact of recognition of depressive symptoms on the course of primary care medicine. Data have been gathered which can begin to answer important questions about depression and its recognition at low cost. Five hundred ten new primary care patients were randomized to either the Family Practice or Internal Medicine Clinic with multiple measures of health, including the Beck Depression Inventory (BDI) and the Medical Outcomes Study Short Form-36 (MOS SF-36). Initial clinic visits were videotaped and each patient was followed for one year before measures were re-administered. Sixteen percent of patients will be given the diagnosis of depression by their primary care providers, projecting from initial data. BDI scores show a significant relationship to the decision to diagnose depression as demonstrated by logistic regression. Power analysis finds these data robust enough to detect real differences ind process and outcome of care for those whose depressive symptoms are recognized and those whose symptoms are recognized and those whose symptoms are not recognized. The following hypotheses are proposed: I: There will be significant differences in the physician-patient interaction depending on whether depressive symptoms are recognized by the physician. II: There will be significant differences in the process and the cost of care depending on whether depressive symptoms are appropriately recognized. III: Recognition of depressive symptoms will have a significant impact on the outcome of care. Results are likely to prove valuable in developing effective training of primary care physicians in the recognition and management of depressive symptoms.